The present invention relates to variable stiffness catheters and more specifically relates to devices and methods for accessing tubular structures in the body. Existing catheters commonly use a guidewire to aid in the positioning thereof within body lumens for the purpose of delivering medical devices or therapeutic agents to treat a variety of medical conditions. Often, the delivery path within the lumens or vessels of a mammalian body can include regions under 2 mm in diameter and may require the distal end of the device to undergo turns of 90 degrees or more to reach the region requiring treatment. Many vascular applications involving the treatment of strokes, aneurysms, or embolizations, for example, involve navigation through the turns that are required, while catheters that are too flexible may kink and thereby complicate proper placement within the body. There are also risks of vessel perforation or vasospasm in procedures that are frequently time sensitive.
Many available catheters have fixed variable stiffness in which the proximal end is stiffer than the distal end. This improves the pushability of the device and also allows the distal end to bend at the required angles. Some devices are made with materials that are preshaped, or alternatively, permit steam shaping of the distal end to improve navigational performance. However, existing devices continue to be limited in the capabilities needed to access small remote locations requiring treatment. Thus, a continuing need exists for improvements in catheter design that enable fast and safe delivery of various treatment options within the mammalian body.